1. Field of the Invention
The present invention relates to an underwater rock boring apparatus having differential global positioning system receiver and underwater rock boring method thereof, and particularly the former in which a differential global positioning system (DGPS) receiver is provided at the body of a boring machine that is installed at the central opening of a self elevation platform (SEP) barge; a location data of the boring machine is received from a satellite and a reference station to bore in the underwater rock at an accurate boring location; and the barge quickly moves to the boring location so that the construction efficiency of the boring work can be enhanced.
2. Description of the Prior Art
In examples, such as a pier groundwork for an underwater bridge structure, a sea structure construction for specific purpose, a development of a waterway for a large ship, and a berth construction for a large ship, the rock existed at the spot in an underway will be bored, a diver loads detonator and charge into the bore—the detonator and charge have a predetermined size and made at the outside, the bore is sealed by an underwater material such as stone, sand, and soil, the explosive is detonated to crush the underwater rock, and finally the spot has to be flattened.
In the boring work, the winches—installed on the barge that has the boring machine—are operated to wind or release the wire ropes. Anchors of above 1.5˜2.5 ton that are connected to respective wire ropes are far away from the barge at more than 150˜200 m. The anchors are dropped on the rock and the barge stops; next the rod of the boring machine is lowered and rotated so that the underwater rock can be bored.
One example of the prior art for the boring of the underwater rock is disclosed in Korean Publication Patent No. 10-0270251. As shown in FIGS. 1a and 1b, at one edge of a barge 1 is installed a platform 4 which is at a predetermined interval and the platform 4 is comprised of a vertical platform 2 and a horizontal platform 3. The rail 5 that is flush with the surface of the barge 1 is installed at the platform 4. A conventional land-boring machine 7 has a casing 6 that operates up and down and has a driving wheel 8 at each end of the land-boring machine 7. Each driving wheel 8 is placed on the rail 5 of the platform 4 and one side edge of the barge 1. The land-boring machine 7 moves longitudinally.
The above prior art assumes the form in which crawler drill used as the land boring machine 7 is loaded on the barge 1, and the platform 4 made from a H-beam is constructed at the one side border of the barge. The crawler drill is placed on the platform and moves forward/backward along the rail 5. The barge and the boring machine can be independently operated so that the boring work is executed.
However, in the boring work of the sea, a barge is swayed 20˜30 cm owing to waves. When a large vessel comes by the barge that is executing the boring work, the height of the wave increases above 60 cm and the force of the wave creates a wide swing of the barge.
Therefore, if the barge rolls or pitches heavily from the power of the wave, in addition to the swing of the barge, the crawler drill loaded on the barge is shaken about the center of the support point of the rod and the bit of the crawler drill. The rod can be broken, which causes a problem with the boring work.
Further, since the crawler drill is located at the side boarder of the platform offset from the center of the barge, there is a potential problem of instability because the rods installed the crawler drill can fall into the underwater.
Furthermore, when a change of the boring position is required, the crawler drill must be moved along the rail, and so the boring equipment is knocked down and then the knockdown parts are assembled at the next target boring position. It is attended with difficulties in the boring work. It normally takes more than 30 minutes to move the next boring position, thus bringing the problem of inefficiency caused by the slow process of the boring work.
In addition, when the length of the rod is about 3 m, and the diameter of the rod is 75 mm, the rod weighs 18 kg. According to the handling of the rod, there is no choice but to adapt the diameter of the rod to have less than 75 mm. (if adapting the diameter of the bit having 105 mm, the weight of the rod increases up to 22 kg, and the center of the machine can be swayed.) There is a limitation in increasing the diameter of the rod. As the blasting hole having a small diameter (e.g. 75 mm) is dug, the position of the digging is inaccurate. And also, since the small diameter of the boring hole has the increased volume of charge, it has the disadvantage that not much blast effect can be obtained.
Furthermore, if the prior art is adopted where a silt of the underwater covers the underwater rock, the silt around the blast hole having the small diameter or the rock debris go into the blast hole, which makes the charge loading difficult. Generally, the blocking ratio of the boring hole amounts to 20˜30% and it requires additional boring work. Otherwise, the charge must stick on the outer surface of the rock, which is inconvenient.
To solve the problem, the inventors suggest new boring technology in which a satellite navigation device orients the accurate position of a target and the device is brought to the underwater boring technology.
In general, Global Positioning System is a system for accurately detecting target's position using a satellite. With the GPS receiver, accurate time and distance from more than 3 satellites are measured; the present position is accurately attained using a triangular method. This is applied to simple positioning information, defense, sea development, investigation of sea resources, automatic navigation for plane, ship, and car, traffic control, prevention of oil tank collision, accurate survey of engineering works, and map production, etc.
DGPS (Differential Global Position System) is a position detecting apparatus by which the satellite signal is received from a satellite and a compensation signal is received from a DGPS reference station that is installed at the already known position of the land. The position of a ship can accurately be detected even in the open sea. The DGPS is a lightweight apparatus, which is comprised of an antenna receiving the satellite signal, a RF (radio frequency) unit extracting the desirable signal from the satellite signal, a computing unit processing the desirable signal, and a user interface unit.
The apparatus is a modular GPS system that can measure the position far from the GPS satellite and the reference station. It can operate continuously for 24 hours. Location information with high accuracy can be attained through the observation process in Real Time Kinematics (RTK) in the quick initialization and the lower power.
Therefore, the present invention is devised to solve the problems. A differential global positioning system (DGPS) receiver is provided at the body of a boring machine that is installed at the central opening of a self elevation platform (SEP) barge, the location of the boring machine is set to concentricity of the target boring position (DGPS boring error; less than 2 cm), and the position of the hull can be controlled without any movement of the boring machine. Then, the barge quickly moves to the next target boring location so that the construction efficiency of the boring work can be enhanced.